Proposed experiments will assess the significance of the post-stress period in the development of stress-induced gastric ulcers in the rat. Specifically, this research will examine the hypothesis that a sudden reversal from stress to rest conditions may result in important physiological and gastric secretory changes which contribute to the ulcerogenic process. This will be accomplished by subjecting Ss to a single, 6-hr., shock-stress condition known to be ulcerogenic, and comparing gastric pathology in groups maintained in stressful (i.e., experimental chamber) and safe (i.e., home cage) environments during a 2-hr. post-stress period. In one experiment, animals will be fitted with chronically implanted gastric fistulas in order to examine the nature of the relationship between secretory processes and gastric pathology.